'use strict';

exports = module.exports = {
    getBackupFilePath,
    download,
    upload
};

const assert = require('assert'),
    async = require('async'),
    BoxError = require('../boxerror.js'),
    DataLayout = require('../datalayout.js'),
    debug = require('debug')('box:backupformat/tgz'),
    { DecryptStream, EncryptStream } = require('../hush.js'),
    once = require('../once.js'),
    path = require('path'),
    progressStream = require('progress-stream'),
    storage = require('../storage.js'),
    tar = require('tar-fs'),
    zlib = require('zlib');

function getBackupFilePath(backupConfig, remotePath) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof remotePath, 'string');

    const rootPath = storage.api(backupConfig.provider).getRootPath(backupConfig);

    const fileType = backupConfig.encryption ? '.tar.gz.enc' : '.tar.gz';
    return path.join(rootPath, remotePath + fileType);
}

function tarPack(dataLayout, encryption) {
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof encryption, 'object');

    const pack = tar.pack('/', {
        dereference: false, // pack the symlink and not what it points to
        entries: dataLayout.localPaths(),
        ignoreStatError: (path, err) => {
            debug(`tarPack: error stat'ing ${path} - ${err.code}`);
            return err.code === 'ENOENT'; // ignore if file or dir got removed (probably some temporary file)
        },
        map: function(header) {
            header.name = dataLayout.toRemotePath(header.name);
            // the tar pax format allows us to encode filenames > 100 and size > 8GB (see #640)
            // https://www.systutorials.com/docs/linux/man/5-star/
            if (header.size > 8589934590 || header.name > 99) header.pax = { size: header.size };
            return header;
        },
        strict: false // do not error for unknown types (skip fifo, char/block devices)
    });

    const gzip = zlib.createGzip({});
    const ps = progressStream({ time: 10000 }); // emit 'progress' every 10 seconds

    pack.on('error', function (error) {
        debug('tarPack: tar stream error.', error);
        ps.emit('error', new BoxError(BoxError.EXTERNAL_ERROR, error.message));
    });

    gzip.on('error', function (error) {
        debug('tarPack: gzip stream error.', error);
        ps.emit('error', new BoxError(BoxError.EXTERNAL_ERROR, error.message));
    });

    if (encryption) {
        const encryptStream = new EncryptStream(encryption);
        encryptStream.on('error', function (error) {
            debug('tarPack: encrypt stream error.', error);
            ps.emit('error', new BoxError(BoxError.EXTERNAL_ERROR, error.message));
        });

        pack.pipe(gzip).pipe(encryptStream).pipe(ps);
    } else {
        pack.pipe(gzip).pipe(ps);
    }

    return ps;
}

function tarExtract(inStream, dataLayout, encryption) {
    assert.strictEqual(typeof inStream, 'object');
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof encryption, 'object');

    const gunzip = zlib.createGunzip({});
    const ps = progressStream({ time: 10000 }); // display a progress every 10 seconds
    const extract = tar.extract('/', {
        map: function (header) {
            header.name = dataLayout.toLocalPath(header.name);
            return header;
        },
        dmode: 500 // ensure directory is writable
    });

    const emitError = once((error) => {
        inStream.destroy();
        ps.emit('error', error);
    });

    inStream.on('error', function (error) {
        debug('tarExtract: input stream error.', error);
        emitError(new BoxError(BoxError.EXTERNAL_ERROR, error.message));
    });

    gunzip.on('error', function (error) {
        debug('tarExtract: gunzip stream error.', error);
        emitError(new BoxError(BoxError.EXTERNAL_ERROR, error.message));
    });

    extract.on('error', function (error) {
        debug('tarExtract: extract stream error.', error);
        emitError(new BoxError(BoxError.EXTERNAL_ERROR, error.message));
    });

    extract.on('finish', function () {
        debug('tarExtract: done.');
        // we use a separate event because ps is a through2 stream which emits 'finish' event indicating end of inStream and not extract
        ps.emit('done');
    });

    if (encryption) {
        const decrypt = new DecryptStream(encryption);
        decrypt.on('error', function (error) {
            debug('tarExtract: decrypt stream error.', error);
            emitError(new BoxError(BoxError.EXTERNAL_ERROR, `Failed to decrypt: ${error.message}`));
        });
        inStream.pipe(ps).pipe(decrypt).pipe(gunzip).pipe(extract);
    } else {
        inStream.pipe(ps).pipe(gunzip).pipe(extract);
    }

    return ps;
}

function download(backupConfig, remotePath, dataLayout, progressCallback, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof remotePath, 'string');
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    debug(`download: Downloading ${remotePath} to ${dataLayout.toString()}`);

    const backupFilePath = getBackupFilePath(backupConfig, remotePath);

    async.retry({ times: 5, interval: 20000 }, function (retryCallback) {
        progressCallback({ message: `Downloading backup ${remotePath}` });

        storage.api(backupConfig.provider).download(backupConfig, backupFilePath, function (error, sourceStream) {
            if (error) return retryCallback(error);

            const ps = tarExtract(sourceStream, dataLayout, backupConfig.encryption);

            ps.on('progress', function (progress) {
                const transferred = Math.round(progress.transferred/1024/1024), speed = Math.round(progress.speed/1024/1024);
                if (!transferred && !speed) return progressCallback({ message: 'Downloading backup' }); // 0M@0MBps looks wrong
                progressCallback({ message: `Downloading ${transferred}M@${speed}MBps` });
            });
            ps.on('error', retryCallback);
            ps.on('done', retryCallback);
        });
    }, callback);
}

function upload(backupConfig, remotePath, dataLayout, progressCallback, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof remotePath, 'string');
    assert.strictEqual(typeof dataLayout, 'object');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    async.retry({ times: 5, interval: 20000 }, function (retryCallback) {
        retryCallback = once(retryCallback); // protect again upload() erroring much later after tar stream error

        const tarStream = tarPack(dataLayout, backupConfig.encryption);

        tarStream.on('progress', function (progress) {
            const transferred = Math.round(progress.transferred/1024/1024), speed = Math.round(progress.speed/1024/1024);
            if (!transferred && !speed) return progressCallback({ message: 'Uploading backup' }); // 0M@0MBps looks wrong
            progressCallback({ message: `Uploading backup ${transferred}M@${speed}MBps` });
        });
        tarStream.on('error', retryCallback); // already returns BoxError

        storage.api(backupConfig.provider).upload(backupConfig, getBackupFilePath(backupConfig, remotePath), tarStream, retryCallback);
    }, callback);
}